Re: 4S QRP Watering Holes!


John Lonigro
 

Charles:

The unique feature of the Pigrig is the narrow crystal filter is also tuned to 7.031 MHz.  The entire rig is designed around that frequency.  Diz was able to do that because it is a single frequency rig.  That's why, for example, you can't easily modify it to use the SAVXO.

72,
John AA0VE

On 03/02/2013 08:57 PM, Charles Moizeau wrote:
 

I've been following this and the Pig Rig thread.  I seems that there are some concerns over being pinned down to one frequency, and it may be that there will be some VXO modifications that will arrive in due time.  There are some well-known techniques for stretching the frequency swing a small bit, e.g., paralleling a second crystal of almost the same frequency and putting one or more inductors in the pulling circuitry.

Of possible interest is an article published in 73 Magazine for March 1996 by Ken Cornell, W2IMB, SK.
The link is:

http://ia700806.us.archive.org/15/items/73-magazine-1996-03/03_March_1996.pdf

Ken used that simplest of oscillators, the Pierce; An MF102, one crystal, five disc capacitors , one resistor, one rf choke and a permeability tuned inductor.  Ken reports being able to swing a 3.57945 mHz color burst crystal some 30 to 40kHz!  The secret was in the sauce and the sauce used litz wire in the inductor
.

My workbench is currently bare for I am presently concerned with post-Sandy repairs and clean-up, but I find myself not too charmed by the mechanics of the described permeability tuning arrangement. 

I'm wondering if the inductor might be litz wire on a toroidal form with the variable tuning supplied by a variable capacitor.  Another thought is that, instead of a variable capacitor, a control winding might be interwound with the litz, and that control winding could be shunted by a rheostat.  Varying the rheostat's resistance would vary the impedance that the control winding would reflect back into the litz winding, and thus change its inductance and the oscillator's frequency.

72,

Charles, W2SH

 




To: 4sqrp@...; davemrtn@...
CC: wa0itp@...; jomatlock@...
From: jonigro@...
Date: Sat, 2 Mar 2013 05:24:47 -0600
Subject: Re: [4sqrp] 4S QRP Watering Holes!

 
Putting the pigrig on 7122 might be super easy, but what happens when you have to move up or down a little when that frequency is busy?

John AA0VE


On 03/01/2013 10:19 PM, David Martin wrote:
 

Never mind, looks like changing crystals would be a whole lot easier.

On 03/01/2013 09:49 PM, David Martin wrote:
 

I hadn't printed schematics yet to see if it's doable, but what about adapting the SAVXO to the Pig Rig ???


On 03/01/2013 08:47 PM, WA0ITP wrote:
 

It will be super easy to put the existing pigrig on 7122 - 4 crystals is all it takes.  My 7040 rocks are all soldered in, may have to change 'em out. 
 
----------------------------------
I love this radio stuff !
72   WAØITP
www.wa0itp.com
www.4sqrp.com
www.qrpspots.com
 
 
----- Original Message -----
Sent: Friday, March 01, 2013 8:42 PM
Subject: [4sqrp] 4S QRP Watering Holes!

He Guys
Well it's neat to see all the excitement that 
has been stirred up with the DiZ Pig Rig!
Now, we need to find some  "Watering Holes  for our group to hang out at so we can go there and see who is calling CQ. 3564 and 7122 seem like candidates for 40 and 80, but how about 20m?
Do we move up a little to 14.062? 
Just a thought for you guys to kick around.
We seem to have a new found presence on the QRP world and I think it would be neat to have a place to meet up on the bands!
Thanks 
Johnny AC0BQ





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